Starch is a complex carbohydrate often found in the human diet. Plants are often used as a source for starch, which can be used to produce ethanol and other products. Plant starches are generally in a granular form, which is insoluble in water. Conventional plant starch processing methods often involve a starch gelatinization process, wherein aqueous starch slurry is heated so that the granular starch in the slurry swells and bursts, dispersing starch molecules into the solution. During the gelatinization process, there is a dramatic increase in viscosity. To enable handling during the remaining process steps, the starch must be thinned or “liquefied”. This reduction in viscosity can be accomplished by enzymatic degradation in a process referred to as liquefaction. During liquefaction, the long-chained starch molecules are degraded into smaller branched and linear chains of glucose units (dextrins) by an enzyme, such as α-amylase (i.e., α-amylase).
Amylase is an enzyme that catalyzes the hydrolysis of starches into sugars. Amylases hydrolyze internal α-1,4-glucosidic linkages in starch, largely at random, to produce smaller molecular weight maltodextrins. Amylases are of considerable commercial value, as they are used in the initial stages (liquefaction) of starch processing; in wet corn milling; in alcohol production; as cleaning agents in detergent matrices; in the textile industry for starch desizing; in baking applications; in the beverage industry; in oilfields in drilling processes; in inking of recycled paper; and in animal feed.